MPCVD grown high quality diamond single crystal film for high-speed solar-blind UV photodetectors with TiC ohmic contacts

Abstract

Single crystal diamond has emerged as promising semiconductor for power electronics, quantum sensing and radiation detection, because of its ultra-wide bandgap, high breakdown field and high stability. In this work, we report the growth of high-quality single crystal diamond film using microwave plasma-enhanced chemical vapor deposition (MPCVD) and the fabrication of metal-semiconductor-metal (MSM) structured photodetectors for solar blind UV light detection. The single crystal diamond film has a full width at half maximum (FWHM) of 80 arcsec and a Raman FWHM of 2.1 cm⁻¹, and a low root mean square (RMS) surface roughness of 0.5 nm. The solar-blind photodetectors (SBPDs) are highly sensitive to solar-blind UV spectrum with the specific wavelength of 222 nm, and achieve a low dark current of 2.3 × 10⁻¹¹ An under 20 V bias, a specific detectivity of 4.4 × 10¹² Jones and a rapid response speed with a decay time of 78.6 μs. The enhanced performance of the SBPDs is attributed to the high crystalline quality of the diamond films and the optimized ohmic contact at the device interface, which facilitates the efficient transport of photogenerated charge carriers. The diamond-based photodetectors with high sensitivity, rapid response and stability have potential applications in the field of space detection, medical diagnosis and environmental monitoring.